Method and device for increasing the shelf life of an oxygen sensitive product

ABSTRACT

A method and a device is provided for increasing the shelf life of an oxygen sensitive product such as ground meat by injecting an inert gas or blend of inert gases into the ground meat through a stopper as meat is being pushed toward the stuffer outlet and a conveyor to a chub packager. By introducing the inert gas at this early stage in the chub packaging operation. the oxygen content within each chub is reduced from about 7% using the prior art method to 0.5% and less using the present invention. The inert gas forces substantially all of the ambient air away from the entire surface area of the ground meat as it is being circulated in the lower portion of the stuffer hopper and prior to being forced out through the stuffer outlet.

FIELD OF INVENTION

[0001] The present invention relates to a method and device forincreasing the shelf life of oxygen sensitive products such as groundbeef and other meat. More particularly, the invention relates to animproved stopper for attachment to the hopper of a stuffer used in thepackaging of such oxygen sensitive food products. The stopper has meansfor purging the ambient air surrounding the product during the stuffingoperation and means for disassembling and cleaning the stopper betweenperiods of use.

BACKGROUND OF THE INVENTION

[0002] As the global demand for processed meat increases, processorscontinue to demand equipment, supplies, and raw material to enhancetheir ability to increase productivity, profits, customer satisfaction,and most importantly sanitation measures. One high-speed packagingsystem for ground meat is a combination of a stuffer with a high-speedchub packaging machine. In this system, the meat, such as beef, iscoarsely ground, i.e., about 9.5 mm to 19.0 mm diameter die cut, anddumped or otherwise conveyed into a hopper of the stuffer or a stuffingpump; see U.S. Pat. Nos. 4,417,434 and 5,830,050, respectively. Thecoarsely ground meat is then conveyed to the chub packaging machine; seeU.S. Pat. Nos. 4,085,778; 4,085,779; and 4,939,885. An example of acommercially available high-speed chub packaging machine is a 4000series KartridgPak chub packager. The chub packager packages the meat,with or without added an inert gas, e.g., carbon dioxide, intooxygen-impermeable casings; see U.S. Pat. No. 4,707,444.

[0003] The chubs usually range from about 4.5 kg to 9.0 kg and have afat content ranging from about 7% to 30%. The chubs are then shipped andstored under refrigeration until needed. In the case of ground beef,they may be distributed to supermarkets that regrind the ground beeffrom the chubs and repackage them in Styrofoam trays, which are overwrapped with a clear plastic film for sale to the consumer. The shelflife of the repackaged product is relatively short. This is primarilydue to the prolonged exposure of the meat product to the residual oxygenpresent in the entire packaging system. It is well known that theprolonged exposure of the meat product to oxygen also bacterial decayand discoloration of the meat.

[0004] It is known to use a modified atmosphere environment whereby apreservation-enhancing gas mixture, typically containing a bacterialinhibitor such as carbon dioxide, is introduced into the casing duringthe chub packaging operation. This method has led to increases in themaximum shelf life of the product of about twenty days.

[0005] It would be desirable to be able extend the shelf life of thepackaged meat within chubs beyond the present maximum shelf life ofabout twenty days, and preferably, up to a maximum shelf life of sixtyor even ninety days.

[0006] One type of commercially available stuffer, e.g., Henry & Sons'AC-20 Continuous Vacuum Stuffer; see web site:http://www.dhenrvandsons.com/index.html for specifications and otherdetails, which information is incorporated herein by reference. Thestuffer comprises a funnel-shaped hopper, a scraper for keeping theground meat from sticking to the inside of the hopper and a stopperattached to the top of the hopper. The scraper is attached to a ringgear connected to a drive mechanism. The ring gear is located in thebottom of the hopper adjacent the outlet and has either a right or aleft spiral. The ring gear causes the scraper to rotate usually in acounterclockwise direction. The combination of the scraper and ring gearforces the ground meat in a downward spiral manner toward the hopperoutlet and the mechanism that feeds the ground meat to the chubpackaging machine. In the commercially available continuous vacuumstuffers, the hopper, ring gear, and stopper are stainless steel and thescraper is an industrial plastic, such as nylon.

[0007] The stopper is usually constructed of hollow tubing, closed ateach end, and protrudes down into the bottom of the hopper adjacent, butnot touching, the ring gear. The stopper stops, or at less slows down,the meat from continuing to spin or rotate around the lower portion ofthe hopper and allows the scrapper and ring rear combination to functionmore efficiently to force the meat out through the stuffer outlet andinto the conveyer to the chub packager. A commercially available stopperconsists of a straight rod extending along the longitudinal axis of thehopper and has extensions, called a paddle, attached to the lower end ofthe rod that is angled at least 15 degrees from vertical. The stopperalso attachment means for fixedly attaching the stopper to the hopper

SUMMARY OF THE INVENTION

[0008] The device and method of the present invention dramaticallyincreases the shelf life of oxygen sensitive food products byintroducing an inert gas during the stuffing stage of the packagingprocess.

[0009] The present invention comprises an improvement in the stuffer inwhich the stopper has means for injecting an inert gas or blend of inertgases into the food product as it is being pushed toward the stufferoutlet. By introducing the inert gas at this early stage in the chubpackaging operation, the oxygen content within each chub is reduced fromabout 7% using the prior art method to 0.5% and less using the presentinvention. Without being bound by the theory of the mechanism, it isbelieved that inert gas forces substantially all of the ambient air awayfrom the entire surface area of the product as it is being circulated inthe lower portion of the stuffer hopper and prior to being forced outthrough the stuffer outlet.

[0010] Preferably, the inert gas or blend of gases is heavier than air.Therefore, the inert gas injected from the stopper displaces the ambientair surrounding the meat entering the hopper and purges the air awayfrom the meat. The remaining oxygen present in the stuffer outlet andconveyor to the chub packager has been found to be dramatically reducedfrom the current operation of adding an inert gas down flow from thestuffer.

[0011] As discussed in further detail in the Examples section below,measurements of the oxygen content in the chubs leaving the packagingmachine has been found to be in the range of about 0.2 to 0.5 volume %oxygen using the device of the present invention. The resulting shelflife of the ground meat has been found to increase to about 90 daysusing the apparatus and method of the present invention.

[0012] In contrast, introducing an inert gas into the casing as thechubs are being formed in the chub packager results in reducing theambient oxygen level from 21% to only about 7-volume %. The resultingshelf life of the ground meat has been found to be about 21 days usingthe apparatus and method of the prior art.

[0013] Various means can be used injecting or otherwise introducing theinert gas during the stuffing operation. One injection means is to placea mesh screen in the hollow stopper connected to a source of inert gaswhere the mesh size of the screen is designed to avoid becoming pluggedwith the product. Another injection means is to place the plurality oforifices along the lower section of the stopper connected to the inertgas source. Preferably, nozzles are placed in the orifices to avoidclogging them with product. Anther injection means is to place eitherthe orifices or the nozzles in the paddle adjacent to the lower end ofthe stopper.

[0014] A still further injection means is to construct the hollowstopper connected to an inert gas supply in at least two sections; (1)the upper section connects to the support at the top of the hopper; and(2) the bottom section having the plurality of holes. A suitablecoupling joins the two sections. The coupling permits the lower sectionto be easily detached from the upper section for cleaning and sanitationprocedures. A further modification of this injection means is to add avertical section that is coupled to the upper section and fixedly attachto the bottom section that includes a paddle.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Further features and advantages will become apparent from thefollowing and more particular description of the preferred embodimentsof the invention, as illustrated in the accompanying drawings in which:

[0016]FIG. 1 is a top and side perspective view of an apparatus of thepresent invention in line with a chub packager and show a stuffer havinga hopper and a stopper in fluid communication with a gas cylinder;

[0017]FIG. 2 is a top view of the hopper shown in FIG. 1;

[0018]FIG. 3 is a partial sectional side view of the hopper shown inFIG. 1 that has been enlarged to show one embodiment of the presentinvention;

[0019]FIG. 4 is a front and side prospective view of the support andflat stopper combination shown in FIG. 3;

[0020]FIG. 5 is a partial sectional side view of the hopper to show apreferred embodiment of the present invention;

[0021]FIG. 6 is top and side perspective view of a modification of thepreferred embodiment of the present invention as it is being assembled;

[0022]FIG. 7 is a perspective top and side view of the assembled stopperof FIG. 6 with a nut lock being slid into place; and

[0023]FIG. 8 is a partial sectional side view of the hopper to showanother modification of the preferred embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

[0024] Referring now to FIGS. 1-3, packaging system 1 includes improvedstuffer 10 upstream of chub packager 20 and cylinder 30 containing aninert gas or a blend of inert gases in fluid communication with stopper40. The inert gas is fed via gas inlet line 44 to funnel shaped hopper50, designed to move ground meat in a downward motion, and is injectedinto the ground meat in stuffer 10 through stopper 40. Preferably hopper50 is at least ¾^(th) full of product and is always maintained at orabove product level 52 shown in FIG. 1.

[0025] Stopper 40 is mounted to attachment means or support 54 attachedto rim 56 of hopper 50 by means of bolts 58, welding or other similarmeans, so that stopper 40 is in a stationary position along thelongitudinal axis through the center of hopper 50.

[0026] In FIG. 3, the internals of hopper 50, in which scrapper 60 andring gear 66 are operably mounted within hopper 50 for movement in acounterclockwise rotation to screw the ground meat toward hopper outlet70 and screw conveyor 74.

[0027] A suitable hopper, scraper, Part #114-080-001 (A-46a), andstainless steel ring gear. Part #114-051-000 (A-32), are designed forthe Continuous Vacuum Stuffer A20 discussed under the Background of theInvention section, and are commercially available from Henry & Sons; seeweb site for additional details, the details of which are incorporatedherein by reference: http://www.dhenrvandsons.com/rings.htm#Scraper.

[0028] Stopper 40 having paddle 80 is mounted within hopper 50 toprevent the ground meat from continuing to rotate in a counterclockwisemanner within hopper 50 and to direct the product into outlet 70.

[0029] In the embodiment shown in FIGS. 1-4, gas inlet line 44 may beconnected to stopper 40 in the following manner. For example, ⅜ inchpolymeric tubing 44 is connected to quick connect fitting 84 inserted in½ inch NPT (National Pipe Thread) nipple 86 treaded into a hole drilledinto 1-⅝ inch stainless steel tubing 88 adjacent to one of connections90 bolted to rim 56 with bolts 58. Support 54 consists of tubing 88welded at each end to tee connections 90. For example stopper 40 is 1-½inch stainless steel tubing and is welded at right angles in the middleof tubing 88. Stopper 40 in this embodiment is basically in the form ofa right angle elbow with horizontal section 92 a extending a foot fromits connection to tubing 88 to the center of hopper 60 and verticalsection 92 b extending along the longitudinal axis of hopper 50.

[0030] In the embodiment shown in FIGS. 3-4, paddle 80 includes flatpiece 94 of stainless steel, i.e., approximately 2-4 inches by 6-8inches, welded to rod 96 that is in turn is welded to end of verticalsection 96. Paddle 80 is at an angle of about 15 to 20 degrees off thelongitudinal axis of stopper 40.

[0031] A section is removed from vertical section 92 b where it connectsto paddle 80 and screen 100 is welded in its place. In this specificembodiment, screen 100 is a tubular section approximately one foot inlength. The tubular section is formed by rolling a multi-mesh screenthat is commercially available from MAP Systems, Inc. into a 1⅝ inchtube to match the diameter of stopper 40. Screen 100 is designed so thatthe product in hopper does not interfere with the passage of the gas. Itis apparent that a number of other types of screens be used to servethis purpose. Various other means for injecting an inert gas into thehopper are described below.

[0032] Vacuum line 120 is operably connected to a means for generating avacuum in conveyor 74 to packager 20. Although stuffer 10 is designed tooperate under vacuum, the device of the present invention is not limitedto vacuum stuffing operations.

[0033] In FIGS. 5-7 a preferred embodiment of stopper of the presentinvention is shown in which flat stopper 140 consists of upper section150, vertical section 156, and paddle section 158 having a plurality ofnozzles 160 screwed into holes 166 drilled into the sides of paddlesection 158 or vertical section 156 or both sections as shown Uppersection 150 forms a smooth arc from its connection to tubing 88 ofsupport 54 to vertical section 156.

[0034] Sanitary connection locking mechanism 170 consists of nut 174that encircles upper section 150 against collar 180, two O-rings 184 forsealing nut 174 to threaded section 190 welded or otherwise fixedlyattached to end 194 of lower section 156.

[0035] In the embodiment shown in FIG. 6, alignment pin 196 a is builtinto threaded section 190 and alignment notch 196 b is built into collar180 adjacent the lower end of upper section 150 for aligning verticaland upper sections. In addition, locking mechanism 170 includes nut lock198 to prevent accidental uncoupling of sealing nut 174 that couldresult in as number of apparent consequences.

[0036] Flat paddle 200 is welded to rod 210 attached to the end ofvertical section 156. In FIG. 5 nozzles 160 are only shown in paddle200, whereas in FIGS. 6 and 7, nozzles are inserted along verticalsection 156 and in paddle section 158. Although the device of thepresent invention is operable for periods of time using only orifices160, the product would tend to plug orifices 160 and require frequentshutdowns for cleaning.

[0037] Nut lock 198 in this embodiment is constructed of ¼ inchhexagonal plate 210 that has 1-½″ hole 212 in the center and 2 tabs 214welded 180° from each other. Hexagonal plate 210 has a ¼″ notch machinedas shown in FIG. 6 to accept ¼ inch locking strip 218 that is welded to1-½ inch upper section 150. Hexagonal plate 210 is shown in FIG. 7sliding down locking strip 218 by gravity to encapsulate nut 174 and tolock it in place.

[0038] The method of operating the device of the present invention shownin FIGS. 1-4 is as follows: As the product is dumped into hopper 50 frommeat carts or on a conveyor, valve 220 is opened on cylinder 30containing an inert gas under pressure. The inert gas comprises carbondioxide, or a blend of inert gases, preferably containing sufficientcarbon dioxide. For example, a blend of 50 vol. % carbon dioxide and 50vol. % nitrogen can be used. The gas is pressurized though inlet gasline 44, quick connect 84, nipple 86 and tubing 88, to stopper 140 fromwhich the gas exits through the plurality of nozzles 160 into theproduct being rotated in the bottom of hopper 50. The rate of inert gaspassing into hopper 50 should be in the range of about 20 to about 100cubic feet per hour. The rate of product from stuffer 10 is in the rangeof about 100 to about 1000 pounds of product per hour. The desired ratioof inert gas to the flow rate of product from stuffer is about 0.05 toabout 0.2 cubic feet per pound of product.

[0039] Typically the product is ground meat that enters hopper 50 is ata temperature slightly below freezing. At these temperatures, it ispreferred that the stopper is spiral stopper 230 having helical orspiral paddle 240 attached to its sides in place of flat paddles 80 or158 as discussed above. FIG. 8 shows spiral stopper 230 in which spiralpaddle 240 consisting of stainless steel in the shape of spiral isattached to the sides of hollow vertical tube 242. A number of holes aredrilled along vertical section 242 and nozzles 250 are mounted withinthe holes as shown in FIG. 8.

[0040] The comparative example and example of the preferred embodimentof the present invention that follows illustrates the unexpected resultsfrom practicing the apparatus of the present invention over that of theprior art. The examples are for illustrative purposes only and are notmeant to limit the scope of the claims in any way.

EXAMPLE Comparative Example

[0041] A Henry & Sons' AC-20 Continuous Vacuum Stuffer was placed inline with a KartridgPak 4000 packaging machine substantially as shown inFIG. 1, but without the modification of the inert gas being injectedinto the stuffer as described above. In this comparative example, groundbeef was dumped into the hopper and fed to chub packager 20 at a rate ofabout 400 pounds per hour. The hopper w as maintained from about 75% to100% full of product at all times during the operation. Carbon dioxideunder a pressure of about 20 psig was pressurized at a rate of 30 to 60cu. ft./hr. into the rope sections of the filled tubular casing priorapplying the clips to from the chubs in the packaging machine. Theoxygen levels in the exterior voids of the chubs leaving the packagingmachine were measured with an oxygen meter and found to be 7 vol. %oxygen.

Example

[0042] The comparative example was repeated using the embodiment of thepresent invention described in the Detailed Description section above inconnection with FIGS. 1-4 e. In this example illustrating the presentinvention, ground beef was dumped into the hopper and fed to chubpackager 20 to maintain the same product level in the hopper and at thesame rate as in the comparative example. Carbon dioxide was injected atthe same rate used in the comparative example into the product in thelower section of hopper 50 as discussed in detail above. The oxygenlevels in the exterior voids of the chubs leaving the packaging machinewere measured with the same oxygen meter and found to be in the rangefrom 0.27 to 0.5 vol. % oxygen, over an order of magnitude less thanthat of the comparative example. This low level of oxygen was found toincrease the shelf life of the resulting chubs from 21 days to 90 days.

[0043] Without departing from the spirit and scope of this invention,one of ordinary skill in the art can make various changes andmodifications to the device of the present invention to adapt it tovarious usages and conditions. As such, these changes and modificationsare properly, equitably, and intended to be, within the full range ofequivalents of the following claims.

What is claimed is:
 1. In a stuffer comprising a funnel-shaped hopperfor directing an oxygen sensitive food product downward having a bottomoutlet, a rotatable scraper for preventing the product from sticking tothe sides of the hopper, means for rotating said scrapper, and a stopperattached to said hopper and extending adjacent the bottom outlet, theimprovement which comprises injection means in said stopper in fluidcommunication with an inert gas source for injecting a flow of inert gaswithin said hopper.
 2. The device of claim 1, wherein said stopperdirects the inert gas into the lower portion of said hopper.
 3. Thedevice of claim 2, wherein said stopper comprises a hollow tube.
 4. Thedevice of claim 3, wherein said hollow tube has a plurality of orificestherein.
 5. The device of claim 4, wherein said hollow tube isdetachable into two sections.
 6. The device of claim 5, wherein saidhollow tube has an upper section having an upper end connected to asource of inert gas and a lower section having the plurality of nozzlesengaged in said orifices.
 7. The device of claim 6, wherein said uppersection is connected to said lower section with a coupling means toreadily detach the lower section for cleaning.
 8. The device of claim 7,wherein said coupling means comprises a threaded section mounted to thelower section, a nut threadably engagable with said threaded sectionencircling said upper section, and a collar at the lower end of saidupper section to stop said nut.
 9. The device of claim 8, wherein saidthreaded section contains an alignment pin, mounted to the lower sectionand an alignment notch adjacent the lower end of said upper section foraligning the lower and upper sections.
 10. The device of claim 9,wherein said coupling means comprises a locking means to preventdecoupling during operation of said stopper.
 11. The device of claim 2,wherein said stopper comprises a hollow tube in fluid communication witha source of inert gas and having a screen for injecting the inert gasinto the lower portion of said hopper.
 12. The device of claim 3,wherein a paddle is fixedly attached to the end of said hollow tube. 13.The device of claim 12, wherein said paddle consists of a flat platefixedly attached to a rod.
 14. The device of claim 12, wherein saidpaddle consists of a flat plate fixedly attached to a hollow tube havinga plurality of orifices therein.
 15. The device of claim 3, wherein aspiral paddle is fixedly attached to said tube.
 16. The device of claim15, wherein said tube has a plurality of orifices therein.
 17. Thedevice of claim 1, wherein the inert gas is carbon dioxide.
 18. Thedevice of claim 1, wherein the inert gas is a blend of carbon dioxideand another inert gas selected from the group consisting of nitrogen,helium, xenon, and mixtures thereof and has a molecular weight ofgreater than
 30. 19. The device of claim 1, wherein ratio of the rate ofinert gas injected into the hopper to the rate of product from thebottom outlet is about 0.05 to about 0.2 cubic feet of inert gas topounds of product.
 20. The method of increasing the shelf life of anoxygen sensitive product sealed in chubs comprising introducing fromabout 20 to 100 cubic feet per minute of an inert gas through a stopperinto a hopper of a stuffer processing ground meat at a rate of about 100to 1000 pounds per hour.
 21. The method of claim 20, wherein the productis ground meat.
 22. The method of claim 20, wherein the product isground beef.
 23. The method of claim 20, wherein the inert gas is carbondioxide.
 24. The method of claim 20, wherein the inert gas is a blend ofcarbon dioxide and another inert gas selected from the group consistingof nitrogen, helium, xenon, and mixtures thereof and has a molecularweight of greater than
 30. 25. The method of claim 20, wherein ratio ofthe rate of inert gas injected into the hopper to the rate of productfrom the bottom outlet is about 0.05 to about 0.2 cubic feet of inertgas to pounds of product.
 26. A stopper attachable to a hopper of astuffer used in the packaging of oxygen sensitive products comprisinginjection means for introducing an inert gas into the lower section ofthe hopper.
 27. The device of claim 26, wherein said stopper comprises ahollow tube in fluid communication with a source of inert gas.
 28. Thedevice of claim 27, wherein said injection means comprises a pluralityof orifices in said hollow tube.
 29. The device of claim 28, whereinsaid hollow tube is detachable into two sections.
 30. The device ofclaim 29, wherein said hollow tube has an upper section having an upperend connected to a source of inert gas and a lower section having theplurality of nozzles engaged in said orifices.
 31. The device of claim30, wherein said upper section is connected to said lower section with acoupling means to readily detach the lower section for cleaning.
 32. Thedevice of claim 31, wherein said coupling means comprises a threadedsection mounted to the lower section, a nut threadably engagable withsaid threaded section encircling said upper section, and a collar at thelower end of said upper section to stop said nut.
 33. The device ofclaim 32, wherein said threaded section contains an alignment pin,mounted to the lower section and an alignment notch adjacent the lowerend of said upper section for aligning the lower and upper sections. 34.The device of claim 32, wherein said coupling means comprises a nutlocking means to prevent decoupling during operation of said stopper.35. The device of claim 27, wherein said injection means comprises ascreen attached within said hollow tube.
 36. The device of claim 27,wherein a paddle is fixedly attached to the end of said hollow tube. 37.The device of claim 36, wherein said paddle consists of a flat platefixedly attached to a rod.
 38. The device of claim 37, wherein saidpaddle consists of a flat plate fixedly attached to a hollow tube havinga plurality of orifices therein.
 39. The device of claim 27, wherein aspiral paddle is fixedly attached to said tube.
 40. The stopper of claim26, wherein said stopper comprises a hollow tube and attachment meansfor attaching said stopper to said hopper
 41. The stopper of claim 40,wherein said attachment means comprises a pair of connections mounted tosaid hopper and tubing attached to said connections and in fluidcommunication with said source of inert gas and said stopper.
 42. Thestopper of claim 41, wherein a gas inlet is connected to said tubing andsaid hollow tube of said stopper is attached to said tubing.
 43. Astopper attachable to a hopper of a stuffer used in the packaging ofoxygen sensitive products comprising a hollow tube in fluidcommunication with a source of inert gas injection means for introducingan inert gas into the lower section of the hopper, said hollow tubebeing detachable into an upper and lower sections, said upper sectionhaving an upper end connected to the source of inert gas and said lowersection having a plurality of nozzles and a coupling means having athreaded section mounted to said lower section, a nut threadablyengagable with said threaded section and encircling said upper section,and a collar at the lower end of said upper section to stop said nut.44. The device of claim 43, wherein said threaded section contains analignment pin, mounted to the lower section and an alignment notchadjacent the lower end of said upper section for aligning the lower andupper sections.
 45. The device of claim 44, wherein said coupling meansalso has a nut locking means to prevent decoupling during operation ofsaid stopper.